OK, learning pros, you'll like this. Students initially learn patterns in lessons. However, to learn patterns well, they need to use them in exercises. Exercises can be inserted in lessons near patterns, in which case it's clear to students which patterns to use. In fact, it's too obvious. They won't have to choose patterns themselves, which is something you want them to learn.
In Skilling, you can put exercises anywhere. For example, you might have a page with only exercises, not bound to any particular lesson. Students will have to figure out what patterns to use.
How do we want them to do that? We could make them flip back through the lessons manually, but that doesn't seem like a good use of their time.
Skilling has a pattern catalog. It's a list of the patterns added by authors. Here's the first entry in the pattern catalog from the web apps course.
When students have an exercise in an exam, or some other out-of-lesson context, they can scan the pattern catalog, to remind them of the patterns they've learned. The last column, "Referenced in," shows the lessons where authors have inserted pattern summaries. If students want more details than the pattern pages have, they can jump to those lessons.
As with everything else, the Skilling software maintains the pattern catalog. Add a pattern, rename one, whatever, and the catalog is updated automatically.